TempStr = input("please input here:")
while TempStr[-1] not in ['N', 'n']:
    if TempStr[-3:] in ["cny", "CNY"]:
        CNY = eval(TempStr[0:-3])
        USD = CNY / 6
        print("{:.2f}CNY is {:.2f}USD".format(CNY, USD))
    elif TempStr[-3:] in ["usd", "USD"]:
        USD = eval(TempStr[0:-3])
        CNY = USD * 6
        print("{:.2f}USD is {:.2f}CNY".format(USD, CNY))
    else:
        print("Your input \"{}\" is not right".format(TempStr))
    TempStr = input("please input here:")
